My high school was the sort that probably had about 15% of the graduating class admitted to an Ivy league school, and probably 70% admitted to a near Ivy, Public Ivy, little Ivy, etc type places. While there were a handful of very, very top kids that just walked away with admission everywhere (and then in most cases didn't even actually go to an Ivy League school), mostly it just seemed kind of random. I knew people with pretty identical backgrounds, grades, and scores where one person got into a certain school and the other got rejected but admitted to a school the first had been rejected at.

The only constant among all of it was that one particular local non-Ivy school that was probably still a top 20 ranked school only accepted 2 kids from my entire 300 person graduating class, and both got in via auditioning through the performing arts college.